Exhaust emissions from internal combustion engines contribute to pollution in the environment. In particular, nitrogen oxide and nitrogen dioxide (collectively, NOx) emissions contribute to smog and acid rain. NOx is a byproduct of the combustion of fossil fuels, and diesel engines generate NOx. Exhaust control systems include features configured to decompose NOx into environmentally friendly or friendlier components such as nitrogen and carbon dioxide. Legislative regulations limit the amount of NOx emissions that a combustion system may generate. Exhaust control systems maintain emissions below regulated levels. When exhaust control systems malfunction, operation of the combustion system is interrupted to effect maintenance or repairs. Such interruptions can be very costly. For example, a truck transporting goods may have to be towed to a maintenance facility hundreds of miles away to effect the repairs.
An exhaust after-treatment system includes a filtering device and a pressure sensor assembly that senses pressure parameters to determine soot loading and filtration efficiency of the filtering device. During cold conditions, water vapor can condense and freeze in pressure sensing tubes of the pressure sensor assembly, causing the pressure sensor assembly to generate pressure signals that are not representative of the condition of the filtration device and cause generation a fault signal. When the fault signal is generated, operation of the combustion system may be interrupted even though the pressure sensor assembly is not necessarily damaged.
There is a need for an improved control system that enables continued operation of the combustion system when iced condition conditions hinder operation of sensors configured to monitor the exhaust after-treatment system.